/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package storm.starter;

import org.apache.storm.Config;
import org.apache.storm.LocalCluster;
import org.apache.storm.LocalDRPC;
import org.apache.storm.StormSubmitter;
import org.apache.storm.drpc.LinearDRPCTopologyBuilder;
import org.apache.storm.topology.BasicOutputCollector;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.topology.base.BaseBasicBolt;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.tuple.Values;

/**
 * This topology is a basic example of doing distributed RPC on top of Storm. It
 * implements a function that appends a "!" to any string you send the DRPC
 * function.
 * 
 * 该拓扑实现了在分布式Storm上处理RPC的方式, 他会为每条RPC的语句后面增加"!"
 * <p/>
 * See https://github.com/nathanmarz/storm/wiki/Distributed-RPC for more
 * information on doing distributed RPC on top of Storm.
 */
public class BasicDRPCTopology {

	public static class ExclaimBolt extends BaseBasicBolt {
		@Override
		public void execute(Tuple tuple, BasicOutputCollector collector) {
			String input = tuple.getString(1);
			collector.emit(new Values(tuple.getValue(0), input + "!"));
		}

		/* 
		 * 该方法定义了emit的输出格式,一旦输出不符合格式会报异常
		 * 此处为输出的一个记录(Values)有2个属性(Field)属性名称分别为(id和result)
		 */
		@Override
		public void declareOutputFields(OutputFieldsDeclarer declarer) {
			declarer.declare(new Fields("id", "result"));
		}

	}

	public static void main(String[] args) throws Exception {
		LinearDRPCTopologyBuilder builder = new LinearDRPCTopologyBuilder("exclamation");
		builder.addBolt(new ExclaimBolt(), 3); // 3个Excuter执行该Bolt,  即3个进程并发实现

		Config conf = new Config();

		if (args == null || args.length == 0) {
			LocalDRPC drpc = new LocalDRPC();
			LocalCluster cluster = new LocalCluster();

			cluster.submitTopology("drpc-demo", conf, builder.createLocalTopology(drpc));

			for (String word : new String[] { "hello", "goodbye" }) {
				System.out.println("Result for \"" + word + "\": " + drpc.execute("exclamation", word));
			}

			cluster.shutdown();
			drpc.shutdown();
		} else {
			conf.setNumWorkers(3);// 由3个work执行该拓扑
			StormSubmitter.submitTopologyWithProgressBar(args[0], conf, builder.createRemoteTopology());
		}
	}
}
